Australia's original 'crocodile hunter', environmentalist and wildlife documentary maker Malcolm Douglas has been killed in a freak car accident in Western Australia's Kimberley.

Police say the 69-year-old was pinned between his four-wheel drive and a tree on a dirt track at his Wilderness Wildlife Park near Broome on Thursday morning.

Detective Sergeant Brett Baddock says it was an unusual set of circumstances.

He says it appears Douglas was standing outside the vehicle when it moved.

"There's no other person involved, it seems the accident just involved Mr Douglas ... in what is very unfortunate circumstances," he said.

"There are no indicators of speed and there are no indicators of alcohol. There are no suspicious circumstances at all."

Special crash investigators from Perth were at the scene.

The Wilderness Wildlife Park, 16 kilometres north of Broome, has been closed until further notice.

Douglas was a great promoter of the Kimberley and had developed two parks near Broome.

The Crocodile Park, close to Cable Beach, was set up in 1983 as a research centre and contained crocodiles that had been caught and relocated to the park, for causing disturbance to outback communities.

Douglas created his Wilderness Wildlife Park on 30 hectares and operated it as an animal refuge with cassowaries, dingoes, kangaroos, birds and hundreds of crocodiles.

He started making wildlife films to showcase his passion for the environment and conservation in 1964.

In an ABC interview, he spoke of his favourite crocodile, dubbed Gamy Leg.

"He's about 4.6 metres - he's a large croc and he'd been attacked by a very big croc and I saved him with lots of steroids," he recalled.

"Not to pump him up, but to get him eating again. And now he's a very aggressive croc. All he wants to do is just kill me - but I don't mind that; I just love him."

Tributes

The Douglas family says it is devastated by the loss of a loving husband, father, son and brother.

"Malcolm was too young to die. He was still so full of life and dreams," the family said in a statement.

"Malcolm was driven by his love of the Australian bush and its wildlife. His work in supporting breeding populations of endangered bilbies was the most recent example of his contribution to the preservation of Australia's fauna."

WA Premier Colin Barnett says the wildlife enthusiast helped teach children about animals and the environment in the north of the country.

"His original documentary and film Across the Top is still one of the all time top rating outback nature films," he said.

"A true adventurer, a true character. He didn't mince his words, he said what he thought and I think he had a great deal of affection in the hearts and minds of people of this country, and particularly of West Australians.

"He has taught many of us, particularly young children, about the north of this country, about the wildlife and the need to preserve and protect it."

Friend and photographer Hugh Brown says Douglas had a "passion for adventure".

"I think his energy, his passion for the Kimberley ... those things made him unique and one of the, if not the first, bushmen in northern Australia," he said.

Acting Broome shire president Chris Mitchell says Mr Douglas's death is a tragedy.

"I've known Malcolm for about 20 to 23 years; a colourful character for the Kimberley and Broome especially, and a great loss," he said.

Douglas leaves behind wife Valerie, two children, and an unrivalled catalogue of films about the Kimberley wilderness.